As an adjunct to my medical school pathology laboratory course, during which the students studied over 100 slides of general and systemic pathology, a wiki was developed. In this wiki, available to all and editable by all, slides were uploaded. In particular, these were usually edited and annotated slides - with underlining, circling and with added descriptive text.
[The wiki host is no longer in existence, so gone is the wiki, but the full description is found in the paper cited below]. The idea still stands.
46. Leifer, Z. (2015). “The Use of Virtual Microscopy and a Wiki in Pathology Education:
Tracking Student Use, Involvement and Response”. J Pathol Inform 2015;6:30.
See also "From my students most of all"